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In today’s world the demand for freshwater, to meet the needs of human activities is growing exponentially. As a result, manufacturers are continuing to make progress in the design and production of efficient desalination and cooling units to optimize and reduce the overall cost of production. In this work, we study the numerical study of the evaporation of a thin liquid film dripping by gravity with constant feed rates in a closed rectangular cavity formed by two parallel flat plates. The wall which supports the liquid film is heated by a constant temperature heating, while the other is kept at a constant and uniform temperature to condense the formed vapor. The results obtained show that the heat transfer in the distillation cell is dominated by the latent heat transfer associated with the evaporation. The results also show that the temperature of the film increases slightly for the heating zone and then decreases over most of the plate for the evaporation zone

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In this paper, the volume of fluid (VOF) method in the OpenFOAM open-source computational fluid dynamics (CFD) package is used to investigate the coupled heat and mass transfer by mixed convection during the evaporation of water-thin film. The liquid film is falling down on the left wall of a vertical channel and is subjected to a uniform heat flux density, whereas the right wall is assumed to be insulated and dry. The gas mixture consists of air and water vapor. The governing equations in the liquid and in the gas areas with the boundary conditions are solved by using the finite volume method. The results which include temperature, velocity, and vapor mass fraction are presented. The effect of heat flux density, liquid inlet temperature, and mass flow rate on the heat and mass transfer are also analyzed. Better liquid film evaporation is noted for the system with a higher heat flux density and inlet liquid temperature or a lower mass flow rate. Therefore, the VOF method describes well the thermal and dynamic behavior during the evaporation of the liquid film.